This invention relates to a vehicular speed responsive power steering device and more particularly, to a vehicular speed responsive power steering device which varies power assist amount depending upon vehicular speed.
There have been proposed a variety of vehicular speed responsive power steering devices such as a power steering device in which a vehicular speed responsive pump operates a cut-off valve and the inner pumping pressure of a main pump operates a reactive plunger, a power steering device in which a vehicular speed responsive pump controls a valve adapted to bypass a supply oil passage and a tank return oil passage, a power steering device in which a valve adapted to bypass a supply oil passage and a tank return oil passage is controlled in proportion to vehicular speed and angular steering rate of steering wheel gripping force, a power steering device in which a bypass pump between the two chambers of an actuator is controlled by a vehicular speed signal or vehicular speed and actual steering angle signals or alternatively by a vehicular speed responsive pump, a power steering device in which a pump flow rate regulation valve is controlled by a solenoid in proportion to vehicular speed, angular steering speed and lateral acceleration, a power steering device in which a pump flow rate regulation valve is controlled by a stepping motor in proportion to vehicular speed and a power steering device in which a variable delivery pump is controlled in proportion to vehicular speed.
However, the prior art power steering devices require complicated components most of which are precision elements and thus, expensive. Furthermore, the prior art power steering devices present the problem that the devices can not easily exhibit performance characteristics called for.